Primary MALT Lymphoma of the Bile Duct

Abstract

Introduction: Primary Non-Hodgkin's lymphoma (NHL) of the common bile duct (CBD) is a rare disease that usually presents with obstructive jaundice. We present the case of a patient who developed painless jaundice and a biliary stricture suspicious for cholangiocarcinoma. He underwent a pancreaticoduodenectomy (Whipple procedure). Post-surgical pathology of bile duct was diagnostic of extranodal mucosa-associated lymphoid tissue (MALT) lymphoma. Case presentation: A 63-year-old male with a history of arthritis, hypertension, COPD, and coronary artery disease was admitted with obstructive jaundice. The preoperative abdominal MRI showed soft tissue prominence around the mid and distal portions of the CBD. This area restricted on the diffusion weighted phase and was concerning for cholangiocarcinoma. The patient underwent a Whipple procedure. Post-surgical pathology from the stricture revealed a dense, nodular infiltrate of small lymphoid cells. These cells were strongly positive for CD45, CD20, PAX5, and BCL2. Many of them expressed kappa light chain with fewer lambda positive cells. The morphologic and immunophenotypic features were diagnostic of low-grade B-cell lymphoma. The lack of CD10 and BCL6 positivity did not favor follicular lymphoma. The low-grade cytologic features of the cells and presence of disrupted expanded follicular dendritic cells favored extranodal MALT lymphoma. In the absence of systemic disease, this represented a primary biliary MALT lymphoma. Discussion: Primary bile duct lymphomas are extremely rare. Most of them are diffuse large B-cell lymphomas. However, some are extranodal marginal zone B-cell lymphomas (as in our case) or follicular lymphomas. Only a few cases of primary MALT bile duct lymphomas have been described. Primary bile duct lymphomas account for less than 1% of all extranodal lymphomas. They typically present with obstructive jaundice. Clinical and radiological features are similar to extrahepatic cholangiocarcinomas. There are no standard treatments given the rarity of the disease. Multiple, deep biopsies from the suspected lesion are necessary for definitive diagnosis. Complications of curative surgery for biliary lymphomas, such as bile leak, hemorrhage, and cholangitis, are associated with a high morbidity rate of 13-42%. Primary NHL of the extrahepatic bile duct should be considered in the differential diagnosis when a patient with obstructive jaundice presents with discrepant imaging findings on CT or MRI and ERCP. An accurate histopathologic diagnosis and surgical resection, if feasible, combined with chemotherapy with or without radiotherapy may be the approach to offer a chance for cure.